1. Technical Field
The present invention relates to semiconductor devices, and particularly to semiconductor devices on flexible substrates.
2. Related Art
In the development of electrooptical apparatuses such as liquid crystal apparatuses, the use of flexible substrates has recently been studied to reduce the size and weight of the apparatuses and to make them flexible and resistant to impact.
JP-A-2004-109975, for example, discloses a technique for producing a flexible thin-film transistor (TFT) display using a metal foil substrate. In addition, JP-A-2006-245091 discloses a method for producing an electrooptical apparatus by a transfer process and a technique based on the application of this method to flexible displays.
The inventors have been engaged in research and development of electrooptical apparatuses using flexible substrates such as resin layers to improve the characteristics of the apparatuses.
An active-matrix substrate (array substrate) for use in the above electrooptical apparatuses, for example, has an array of pixels including TFTs and pixel electrodes. The TFTs and the pixel electrodes are provided by forming an inorganic insulating film, such as a silicon oxide film or a silicon nitride film, over the entire surface of a glass substrate as a base insulating film and then forming various other films thereon.
If TFTs and pixel electrodes are provided on a base insulating film formed over the entire surface of a flexible substrate, however, a mechanical or thermal stress may cause a crack in the base insulating film and the TFTs formed thereon because of the difference in flexibility between the flexible substrate and the base insulating film, thus degrading the characteristics of the apparatus.